I have a new home (first owner), forced air heat. After the furnace runs for a bit and then shuts down, there is a distinct dripping sound coming from the celing. There are no water pipes there...just the air ducting. I am told this could be condensation forming in the ducts. If this is the case....should there be condensation forming in the ducting? does the build up of condensation lead to problems down the road (mildew, mold, etc) that I should be concerned with? is there a resolution to the very annoying drip sound that I should expect the builder to employ in order to fix this issue?